Turbine shroud segment with load distribution springs

ABSTRACT

A turbine shroud adapted for use in a gas turbine engine includes a plurality of metallic carrier segments and a plurality of blade track segments mounted to corresponding metallic carrier segments. Cooling air is directed onto the blade track segments to cool the blade track segments when exposed to high temperatures in a gas turbine engine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 62/186,114, filed 29 Jun. 2015, the disclosure ofwhich is now expressly incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to gas turbine engines, andmore specifically to turbine shrouds used to seal around turbine wheelsin gas turbine engines.

BACKGROUND

Gas turbine engines are used to power aircraft, watercraft, powergenerators, and the like. Gas turbine engines typically include acompressor, a combustor, and a turbine. The compressor compresses airdrawn into the engine and delivers high pressure air to the combustor.In the combustor, fuel is mixed with the high pressure air and isignited. Products of the combustion reaction in the combustor aredirected into the turbine where work is extracted to drive thecompressor and, sometimes, an output shaft.

Compressors and turbines typically include alternating stages of staticvane assemblies and rotating wheel assemblies. The rotating wheelassemblies include disks carrying blades around their outer edges. Whenthe rotating wheel assemblies turn, tips of the blades move along bladetracks included in static shrouds that are arranged around the rotatingwheel assemblies. Such static shrouds may be coupled to an engine casethat surrounds the compressor, the combustor, and the turbine.

Some shrouds positioned in the turbine may be exposed to hightemperatures from products of the combustion reaction in the combustor.Such shrouds sometimes include components made from materials, forexample metallic and ceramic composites, that have differentcharacteristics which lead to design challenges.

SUMMARY

The present application discloses one or more of the features recited inthe appended claims and/or the following features which, alone or in anycombination, may comprise patentable subject matter.

According to the present disclosure, a turbine shroud for use in a gasturbine engine may include a plurality of shroud segments each arrangedto extend at least partway around a central axis of the engine. Thecarrier segment may be formed to define an attachment-receiving space.The blade track segment may be coupled to the carrier segment to closethe attachment-receiving space.

In illustrative embodiments, an attachment assembly may be configured tohold the blade track segment on the carrier segment. The attachmentassembly may include an attachment post coupled between the blade tracksegment and the carrier segment, an attachment portion coupled to theattachment post, and a load distributor. The attachment assembly may beconfigured to apply a clamp force between the carrier segment and a sealsegment onto a seal member. The load distributor may be configured toregulate the clamp force during operation of the engine.

These and other features of the present disclosure will become moreapparent from the following description of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away perspective view of a gas turbine engine showingthat the engine includes a fan, a compressor, a combustor, and aturbine, the turbine including a turbine shroud in accordance with thepresent disclosure positioned radially outward from blades of a turbinewheel assembly as shown in FIG. 2;

FIG. 2 is a partial sectional view of the gas turbine engine of FIG. 1showing that the turbine shroud couples with an outer case of the engineto surround the turbine wheel assembly and suggesting that cooling airis delivered to the turbine shroud at a lower pressure than the hot,high-pressure gasses flowing along a flow path of the engine;

FIG. 3 is an exploded perspective assembly view of one turbine shroudsegment included in the turbine shroud of FIG. 2 showing that theturbine shroud segment includes a carrier segment and a blade tracksegment coupled to the carrier segment by a track-segment coupler;

FIG. 4 is a cut-away perspective view of the assembled shroud segmentshowing that the blade track segment closes a cavity defined by thecarrier segment and suggesting that a seal member is engaged with theblade track segment and the carrier segment to seal the cavity;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4 showing thatthe track-segment coupler includes a support shaft extending through thecarrier segment and blade track segment and a flow distributor coupledto the support shaft to hold the blade track segment on the carriersegment and suggesting that cooling air is directed through thetrack-segment coupler and onto a radially-outward facing side of arunner included in the blade track segment to cool the blade tracksegment;

FIG. 6 is an enlarged view of the seal segment of FIG. 5 showing thatthe seal member is received in a channel of the carrier segment andsuggesting that high-pressure air is delivered to the channel to blockgasses of the flow path from entering the cooling cavity of the turbineshroud segment;

FIG. 7 is a radially-outward looking perspective view of the carriersegment of FIG. 5 showing that the channel includes a groove and aplurality of inlets and suggesting that dams extend across the groove todivide the channel into sections having different pressures;

FIG. 8 is a sectional view taken along line 8-8 in FIG. 4 showing that atrack biaser, provided illustratively by a single wave spring, isengaged between the flow distributor and the blade track segment andsuggesting that the track biaser forces the blade track segment radiallyoutward against the seal member;

FIG. 9 is a view similar to FIG. 8 showing an alternative embodiment ofa track biaser, provided illustratively by a wave spring with varyingfrequency and amplitude;

FIG. 10 is a view similar to FIG. 3 showing an alternative embodiment ofa track biaser, provided illustratively by two wave springs;

FIG. 11 is a sectional view of another embodiment of a turbine shroudsegment for use in the engine of FIG. 1 showing that the turbine shroudsegment includes a carrier segment and a blade track segment coupled tothe carrier segment by a track-segment coupler;

FIG. 12 is a sectional view taken along line 12-12 in FIG. 11 showingbiasing springs included in the shroud segment;

FIG. 13 is a view similar to FIG. 5 showing another embodiment of a sealmember included in a shroud segment like that in FIG. 5; and

FIG. 14 is a view similar to FIG. 13 showing another embodiment of aseal member included in a shroud segment like that in FIG. 5.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to a number of illustrativeembodiments illustrated in the drawings and specific language will beused to describe the same.

An illustrative aerospace gas turbine engine 10 includes a fan 12, acompressor 14, a combustor 16, and a turbine 18 as shown in FIG. 1. Thefan 12 is driven by the turbine 18 and provides thrust for propelling anair vehicle. The compressor 14 compresses and delivers air to thecombustor 16. The combustor 16 mixes fuel with the compressed airreceived from the compressor 14 and ignites the fuel. The hot,high-pressure products of the combustion reaction in the combustor 16are directed into the turbine 18 to cause the turbine 18 to rotate abouta central axis A and drive the compressor 14 and the fan 12.

The turbine 18 includes at least one turbine wheel assembly 11 and aturbine shroud 20 positioned to surround the turbine wheel assembly 11as shown in FIGS. 1 and 2. The turbine shroud 20 is coupled to an outercase 15 of the gas turbine engine 10. The turbine wheel assembly 11includes a plurality of blades 13 coupled to a rotor disk for rotationtherewith. The hot, high pressure combustion products from the combustor16 are directed toward the blades 13 of the turbine wheel assemblies 11along a flow path 17. The blades 13 are in turn pushed by the combustionproducts to cause the turbine wheel assembly 11 to rotate; thereby,driving the rotating components of the compressor 14 and/or the fan 12.

The turbine shroud 20 extends around the turbine wheel assembly 11 toblock combustion products from passing over the blades 13 withoutpushing the blades 13 to rotate as suggested in FIG. 2. In theillustrative embodiment, the turbine shroud 20 is made up of a number ofshroud segments 22, one of which is shown in FIGS. 3 and 4, that extendonly part-way around the central axis A and cooperate to surround theturbine wheel assembly 11. The shroud segments 22 are sealed against oneanother, such as by strip seal members, to provide a continuous turbineshroud 20. In other embodiments, the turbine shroud 20 is annular andnon-segmented to extend fully around the central axis A and surround theturbine wheel assembly 11. In yet other embodiments, certain componentsof the turbine shroud 20 are segmented while other components areannular and non-segmented.

Each shroud segment 22 includes a carrier segment 24, a blade tracksegment 26, and track-segment coupler 28 (sometimes called an attachmentassembly) as shown in FIG. 2. The carrier segment 24 is configured tosupport the blade track segment 26 in position adjacent to the blades 13of the turbine wheel assembly 11. The blade track segment 26 isgenerally concentric with and nested into the carrier segment 24 alongthe central axis A of the gas turbine engine 10. The track-segmentcouplers 28 are configured to hold the blade track segment 26 on thecarrier and to direct a flow of low-pressure (P_(L)) cooling air towarda radially-outward facing side, hereinafter referred to as a backside53, of the blade track segment 26.

In the illustrative embodiment, a seal member 58 is positioned betweenthe backside 53 of the blade track segment 26 and the carrier segment 24to seal a cavity 34 (sometimes called an attachment-receiving space)defined by the carrier segment as suggested in FIG. 2. The seal member58 creates a continuous seal along a perimeter edge of a runner 52 ofthe blade track segment 26 as suggested in FIG. 3. The runner 52 isconfigured to block hot gasses traveling along flow path 17 from passingover the blades 13 without interacting with the blades 13 when theshroud segments 22 are coupled to the outer case 15 as suggested in FIG.2.

The track-segment coupler 28 biases the blade track segment 26 towardthe carrier segment 24 for mutual engagement with the seal member 58 assuggested in FIG. 2. The track-segment couplers 28 are part of alow-pressure cooling system of the engine 10 to direct a flow oflow-pressure cooling air into the cavity 34 of the carrier segment 24 tocool the blade track segment 26. The seal member 58 is configured toblock leakage of hot, high-pressure gases of flow path 17 into thecavity 34 and may be pressurized with high-pressure (P_(H)) air tofurther block such leakage as suggested in FIGS. 5 and 6.

In some embodiments, interstage bleed air from the compressor 14 is usedto supply the flow of cooling air. Using interstage bleed air to coolthe turbine shroud segments 22 may provide a reduction in engineSpecific Fuel Consumption (SFC), in that there is less work in producinginterstage compressor bleed air compared to compressor discharge air andless air can be used because it is cooler. Interstage compressor bleedair is also lower pressure, cooler, and less parasitic than compressordischarge air when used to cool the blade track segments 26. Forexample, the low-pressure cooling air may be at a lower pressure thanthe air in the flow path 17 at the fore end of the turbine section wherethe shroud 20 is located, but at a higher pressure than the air in theflow path 17 aft of the turbine section after work has been done on theturbine wheel 11.

In the illustrative embodiment, each of the carrier segments 24 includesa body 32 formed to define the cavity 34 and case hangers 36 coupled tothe body 32 as suggested in FIGS. 2 and 3. The body 32 includes a mountplate 35 and receiving walls 37 a, 37 b, 37 c, 37 d extending radiallyinward from the mount plate as suggested in FIG. 4. The mount plate 35and receiving walls 37 a, 37 b, 37 c, 37 d cooperate to define thecavity 34. The case hangers 36 are spaced apart from one another andcouple the carrier segments 24 to the outer case 15 of the engine 10 asshown in FIG. 2. The track-segment couplers 28 extend through the body32 and are configured to pass the flow of cooling air into the cavity34.

Each blade track segment 26 includes a runner 52 defining the backside53 and a bridge 54 (sometimes called an attachment portion or box)extending radially outward from and circumferentially along the runner52 as shown in FIG. 3. An internal cooling cavity 56 is defined betweenthe bridge 54 and runner 52. In the illustrative embodiment, a layer 55of Environmental Barrier Coating (EBC) extends around the perimeter edgeof the runner 52 on the backside 53. The EBC layer 55 may provide asealing surface maximize sealing between the seal member 58 and bladetrack segment 26. The EBC also functions to resist overcooling of theperimeter edge of the blade track segment 26 due to seal leakage.Overcooling can lead to higher thermal gradients across the blade tracksegment 26. This can be important where ceramic-matrix composite (CMC)materials are used since CMC has lower stress allowables than, forexample, a nickel based alloy.

The track-segment coupler 28 engages with the bridge 54 and the body 32to hold the blade track segment 26 on the carrier segment 24 assuggested in FIG. 2. The track-segment coupler 28 includes a supportshaft 62 (sometimes called an attachment post), a flow distributor 66(sometimes called an attachment support), and a track biaser 64(sometimes called a load distributor) as suggested in FIG. 3. A radiallyouter portion of the support shaft 62 extends through an opening 38(sometimes called a post hole) formed through the body 32 of the carriersegment 24 and engages with a nut 68 to hold the support shaft 62 on thecarrier segment 24. In the illustrative embodiment, the nut 68 andsupport shaft 62 engage by a threaded connection, though otherconnections are possible.

In some embodiments, a washer 51 and a gasket 59 are positioned betweenthe nut 68 and body 32 to seal the opening 38 around the support shaft62 as suggested in FIG. 3. In the illustrative embodiment, a flange 67of the support shaft 62 engages with the body 32 and cooperates with thenut 68 to hold the support shaft 62 in place relative to the carriersegment 24 as suggested in FIG. 5. In some embodiments, a gasket 71 ispositioned between the flange 67 and body 32 to seal the opening 38around the support shaft 62.

The track biaser 64 and flow distributor 66 extend into the internalcooling cavity 56 of the blade track segment 26 as suggested in FIG. 3.The bridge 54 of the blade track segment 26 is formed to include anopening 57 (sometimes called an attachment hole) configured to receive aradially inner portion of the support shaft 62. The track biaser 64 isformed to include an aperture 74 also configured to receive the radiallyinner portion of the support shaft 62. The radially inner portion of thesupport shaft 62 extends through the opening 57 and the aperture 74, andengages with a shaft receiver 82 of the flow distributor 66. In someembodiments, the support shaft 62 and shaft receiver 82 engage by athreaded connection, though other connections are possible. For example,the support shaft 62 and shaft receiver 82 may be brazed or weldedtogether. In some embodiments, the support shaft 62 engages with theflow distributor 66 prior to coupling with the carrier segment 24.

When assembled, the track-segment coupler 28 is configured to hold theblade track segment 26 on the carrier segment 24 as suggested, forexample, in FIG. 4. The track biaser 64 is forced into engagement withthe bridge 54 by the flow distributor 66 and support shaft 62 to biasthe blade track segment 26 toward the carrier segment 24. The trackbiaser 64 is configured to maintain engagement of the blade tracksegment 26 and carrier segment 24 with the seal member 58 duringoperation of the engine 10. For example, temperature fluctuations maycause the blade track segment 26 and carrier segment 24 to thermallyexpand or contract. Depending on the material, the blade track segment26 and carrier segment 24 may expand or contract at different rates. Thetrack biaser 64 accounts for the difference in expansion or contractionto maintain sealing engagement of the components.

The track biaser 64 may take many forms, such as coil, leaf, wave, ortorsional springs for example. In the illustrative embodiment, the trackbiaser 64 is a wave spring extending along the flow distributor 66 assuggested in FIG. 8. The track biaser 64 fills a gap between the flowdistributor 66 and bridge 54 of the blade track segment 26 to space theflow distributor 66 from the bridge 54. The wave spring track biaser 64is formed to include peaks and valleys. A stiffness of the track biaser64 may be adjusted based on the frequency (i.e., distance betweenadjacent peaks) and/or the amplitude (i.e., natural radial distancebetween adjacent peaks and valleys) of the track biaser 64.

In one example, another embodiment of a track biaser 64 a is shown inFIG. 9. The track biaser 64 a has a longer wavelength (i.e., less stiff)near the support shaft 62 and a shorter wavelength (i.e., more stiff)near the opposing circumferential ends of the track biaser 64 a. Yetanother embodiment of a track biaser 64 b is shown in FIG. 10. The trackbiaser 64 b includes a first half 92 and a second half 94 which eachhave cooperating notches to define the aperture 74 for receiving thesupport shaft 62. Splitting the track biaser 64 b into two halves 92, 94reduces localized stresses on the bridge 54 around the support shaft 62.

The seal member 58 is received in a channel 40 of the carrier segment 24to maintain alignment of the seal member 58 around the perimeter edge ofthe runner 52 as suggested in FIGS. 4 and 5. In the illustrativeembodiment, the channel 40 is generally aligned along the EBC layer 55of the blade track segment 26 to position the seal member 58 forengagement therewith. The channel 40 includes a pair of platforms 44spaced apart from one another to define a groove 42 as suggested in FIG.6. In some embodiments, reliefs 46 are formed along the platforms 44opposite of the groove 42.

High-pressure (P_(H)) air (sometimes called buffer air) is fed throughone or more inlets 31 (sometimes called a buffer air passageway) and oneor more ports 39 to fill the groove 42 and distribute the high-pressureair along the seal member 58 as suggested in FIGS. 5 and 6. In theillustrative embodiment, the seal member 58 includes a plurality ofpassages 48 (sometimes called bleed holes) extending radially throughthe seal member 58 as suggested in FIGS. 3 and 6. In some embodiments,the passages 48 are each aligned with an inlet 31.

During normal operation of engine 10, the seal member 58 blocks gassestraveling along the flow path 17 from entering the cavity 34, and thehigh-pressure air in the groove 42 is dead-headed against the sealmember 58 to minimize the SFC of the engine 10. If the seal formed bythe seal member 58 is broken, the high-pressure air in the groove 42would then flow through the passages 48 to drive the gasses back intothe flow path 17. The platforms 44 define narrow faces to establish ahigh contact pressure on the seal member 58 to contain the high-pressureair in the groove 42.

The high-pressure air is continuously supplied through the inlet 31 tothe groove 42 and is at a higher pressure than the gasses in the flowpath 17 to block entry of the hot gasses into the turbine shroud 20 assuggested in FIG. 5. In some embodiments, the groove 42 is divided intosections 45, 47, 49 by forming dams 41, 43 in the groove 42 between theplatforms 44 as suggested in FIG. 7. The groove 42 may be divided suchthat each section 45, 47, 49 is pressurized corresponding to thepressure of the gasses in the flow path 17 at a similar axial location.The location of the ports 39 may vary depending on the sealingarrangement desired. For example, in some embodiments, the ports 39 areonly positioned along a leading edge of the carrier segment 24. In someembodiments, the ports 39 are positioned along a leading edge andaxially along circumferential edges of the carrier segment 24 aft of theleading edge but forward of the trailing edge of the carrier segment. Insome embodiments, the ports 39 are located all the way around the cavity34. Other locations for the ports 39 are also contemplated.

In one example, the gasses in the flow path 17 fore of the turbineshroud 20 may be at a high-pressure, and section 45 of groove 42 iscorrespondingly at a high-pressure (P_(H)). The gasses in the flow path17 between the fore and aft ends of the turbine shroud 20 may be at amedium-pressure, and section 47 of groove 42 is correspondingly at amedium-pressure (P_(M)). The gasses in the flow path 17 aft of theturbine shroud 20 may be at a low-pressure, and section 49 of groove 42is correspondingly at a low-pressure (P_(L)).

In some embodiments, the pressure in the sections 45, 47, 49 of thegroove 42 is some margin above the pressure in the flow path 17 at asimilar axial location to prevent gasses in the flow path 17 fromentering the cavity 34. For example, the sections 45, 47, 49 may be at apressure about 5% to about 10% above the pressure in the flow path 17 ata similar axial location. The cavity 34 may be at a pressure about 5% toabout 10% above the pressure in the flow path 17 at the aft end of theturbine shroud 20. This enables lower internal cavity pressure and makesthe system more robust to seal leakage flows.

Low-pressure (P_(L)) cooling air flows through the track-segment coupler28 to impinge on the backside 53 of the blade track segment 26 assuggested in FIG. 5. The support shaft 62 includes an outer opening 61and an inner opening 63 spaced radially inward of the outer opening 61.A passageway 65 interconnects the outer opening 61 with the inneropening 63. The flange 67 extends around a perimeter of the supportshaft 62 between the outer and inner openings 61, 63. When assembled,the flow of low-pressure cooling air enters through a port 69 formedthrough the body 32 of the carrier segment 24 and into the outer opening61. The flow of low-pressure cooling air flows through the passageway 65and out of the inner opening 63 into the flow distributor 66.

The flow distributor 66 is configured to distribute the flow oflow-pressure cooling air along the blade track segment 26 to be impingedon the backside 53 as suggested in FIGS. 5 and 8. The flow distributor66 includes flow channels 84 formed internally and circumferentiallyspaced along the flow distributor 66. The flow channels 84 are connectedby distribution channels 88. In the illustrative embodiment, at leastsome of the flow channels 84 are aligned with the inner opening 63 ofthe support shaft 62 to receive the flow of cooling air. In someembodiments, annular grooves are formed in the carrier segment 24 andflow distributor 66 to align with the outer opening 61 and inner opening63, respectively. The annular grooves may allow cooling air to flowaround the support shaft 62 such that the outer opening 61 and inneropening 63 may fluidly communicate with the port 69 and the flowchannels 84 even if misaligned therewith.

A plurality of impingement holes 86 are formed in the flow distributor66 to direct the flow of cooling air in the flow channels 84 toward thebackside 53 of the blade track segment 26. An impingement hole 87 isalso formed at the inner end of the support shaft 62 to direct andimpinge cooling air onto the backside 53 of the blade track segment 26.In the illustrative embodiment, the impingement holes 86, 87 areconfigured to direct the flow of cooling air in a radially inwarddirection toward the runner 52 of the blade track segment 26. In someembodiments, the impingement holes 86, 87 are configured to direct theflow of cooling air toward the runner 52 at an angle relative to theradial direction.

As the cooling air flows through the track-segment coupler 28, thecavity 34 of the carrier segment 24 becomes pressurized as suggested inFIG. 5. In the illustrative embodiment, cooling air discharge ports 33are formed through the body of the carrier segment 24 along an aft sideof the shroud segment 22 to allow the used cooling air to escape fromthe cavity 34 and flow into the primary flow path 17 through the engine10. In some embodiments, the discharge ports may be formed through theseal member 58 or the blade track segment 26 along the aft side of theshroud segment 22. In the illustrative embodiment, an extension 72 ofthe carrier segments 24 cooperates with an arm 72 coupled to the outercase 15 such that un-used cooling air flowing into port 69 is separatedfrom used cooling air flowing out of the discharge ports 33 as suggestedin FIG. 2. A seal member 78 may be positioned to seal against the arm 72and the extension 78.

The blade track segments 26 are illustratively formed fromceramic-containing materials as suggested in FIG. 5. In someembodiments, the blade track segments 26 are formed from ceramic-matrixcomposite materials (particularly silicon-carbide/silicon-carbideceramic-matrix composite materials). The carrier segments 24 andtrack-segment couplers 28 are illustratively formed from metallicmaterials, such as a Ni alloy for example. The seal member 58 andgaskets 59, 71 are illustratively formed from Mica.

Another embodiment of a track-segment coupler 228 as part of a turbineshroud segment 222 is shown in FIGS. 11 and 12. A carrier segment 224 ofthe turbine shroud segment 222 is similar to the carrier segment 24, andsimilar numbering in the 200 series is used to identify common elementsexcept as further detailed below. The shroud segment 222 includes thecarrier segment 224, a blade track segment 226, and the track-segmentcoupler 228.

The blade track segment 226 includes a runner 252, a bridge 254(sometimes called an attachment portion or box), and tubes 251, 256, 259as suggested in FIG. 11. The bridge 254 and tubes 251, 256, 259 eachextend radially outward from and circumferentially along the runner 252as suggested in FIGS. 11 and 12. The tubes 251, 256, 259 are positionedbetween the bridge 254 and the runner 252 and define internal cavities.

In the illustrative embodiment, the track-segment coupler 228 (sometimescalled an attachment assembly) includes three track biasers 262, 264,266 as suggested in FIG. 12. Track biaser 264 will be described indetail, which applies equally to the other track biasers 262, 266. Trackbiaser 264 includes a stem 261 (sometimes called an attachment post), aspring 263 (sometimes called a spring member), and a clip 265 (sometimescalled an attachment support). The stem 261 includes a shaft 268 and aflange 267 extending around a perimeter of the shaft 268.

The shaft 268 of the stem 261 extends through an opening 238 of thecarrier segment 224 and an opening 257 (sometimes called an attachmenthole) of the blade track segment 226 as shown in FIG. 12. In someembodiments, a gasket 269 engages with the carrier segment 224 to sealthe opening 238. The clip 265 is coupled to a radially inner end of theshaft 268 and is positioned inside the tube 256. The spring 263 isconfigured to engage with the flange 267 of the stem 261 to bias thestem 261 radially outward. The clip 265 is configured to engage with thetube 256 to force the blade track segment 226 against a seal member 258as the spring 263 biases the stem 261 outward. In the illustrativeembodiment, the clip 265 is yoke-shaped and contacts the tube 256 atlocations spaced apart from the opening 257. Whereas the track biasers264, 266 are associated with the tube 256, track biaser 262 isassociated with the tube 251 as suggested in FIG. 11. Spring 263 isillustratively shown as a helical compression spring. In someembodiments, other springs are used, such as a machined spring or otherspring shape having a low stiffness.

The track biasers 262, 264, 266 are circumferentially spaced from oneanother to provide support and sealing pressure along the blade tracksegment 226 as suggested in FIG. 12. Similarly, the track biasers 264,266 are axially spaced from the track biaser 262 to provide support andsealing pressure across the blade track segment 226 as suggested in FIG.11. The track biasers 262, 264, 266 are compliant to maintain supporteven during relative thermal expansion or contraction of the componentsof the shroud segment 222. Positioning a majority of the track-segmentcoupler 228 components outside of a cavity 234 (sometimes called anattachment-receiving space) of the carrier segment 224 may maximizetemperature control thereof and allow a height of the bridge 254 to beminimized.

Another embodiment of a seal member 358 as part of a turbine shroudsegment 322 is shown in FIG. 13. The turbine shroud segment 322 issimilar to the turbine shroud segment 22, and similar numbering in the300 series is used to identify common elements except as furtherdetailed below. The seal member 358 is a metallic W-shaped spring sealwhich is formed in an annular configuration to extend along a perimeteredge of a blade track segment 326 of the turbine shroud segment 322.

In the illustrative embodiment, the seal member 358 is folded into twoU-shaped channels defining two opposing ends 396 and two peaks 398 assuggested in FIG. 13. While two peaks 398 are shown, more or less peaksmay be used. The seal member 358 is formed such that the ends 396 arebiased away from one another. In the illustrative embodiment, the sealmember 358 is received in a channel 340 formed in a carrier segment 324of the turbine shroud segment 322. The ends 396 engage with the channel340 to seal against the carrier segment 324, and the peaks 398 engageand seal against an EBC layer 355 on the blade track segment 326 to seala cavity 334. In some embodiments, no EBC layer 355 is used and thepeaks 398 engage and seal against a runner 352 of the blade tracksegment 326 to seal the cavity 334. An inlet 331 directs high-pressureair into the channel 340 to block ingress of air from the flow path 17if the seal is broken. The high-pressure air may energize the sealmember 358 to maximize sealing contact.

In another embodiment, seal members 458 a, 458 b are used as part of aturbine shroud segment 422 as shown in FIG. 14. The turbine shroudsegment 422 is similar to the turbine shroud segment 22, and similarnumbering in the 400 series is used to identify common elements exceptas further detailed below. The seal member 458 is a metallic multi-foldspring seal which is formed in an annular configuration to extend alonga perimeter edge of a blade track segment 426 of the turbine shroudsegment 422.

In the illustrative embodiment, the seal members 458 a, 458 b are eachfolded into four U-shaped channels defining two opposing ends 496 andfour peaks 498 as suggested in FIG. 14. While four peaks 498 are shown,more or less peaks may be used. Each seal member 458 a, 458 b is formedsuch that the ends 496 are biased away from one another. The sealmembers 458 a, 458 b are received in a channel 440 formed in a carriersegment 424 of the turbine shroud segment 422. The seal members 458 a,458 b are spaced apart from one another such that they run alongopposing sides of the channel 440 from one another. The ends 496 of eachseal member 458 a, 458 b engage and seal against the channel 440 and anEBC layer 455 on the blade track segment 426, and the peaks 498 engageand seal against the channel 440 to seal a cavity 434. An inlet 431directs high-pressure air into the channel 440 between the seal members458 a, 458 b to block ingress of air from the flow path 17 if the sealis broken. The high-pressure air may energize the seal members 458 a,458 b to maximize sealing contact.

In illustrative embodiments, the carrier segments may include end capsconfigured to receive strip seals. In some such embodiments, a multiplestrip seal arrangement may include radially extending strip seals andaxially extending strip seals. The axially extending strip seals may beplaced along the radial inner and outer edges of the carrier segments.Including a strip seal along the radially outer edge of the carrier cangreatly reduce the leakage flow through all of the adjacent strip seals.In some embodiments, a 45% reduction in strip seal flow with theaddition of the strip seal along the outer edge of the carrier segmentsmay be achieved. In some embodiments, grooves are formed in the end capsto receive the strip seals.

Compared to Ni alloys for example, CMCs have very low allowable stressvalues. Blade track segments (sometimes called seal segment) in gasturbine engines can have significant pressure loads. In order to be ableto minimally load the seal segment, the pressure in the receiving cavityof a carrier segment can be much lower than the flow path pressure atthe same location. Temperature gradients and contact loads can beminimized to accommodate the low strength of CMC material andcircumferential span of the seal segments.

In illustrative embodiments, high-pressure buffering passages block hotair ingresses into the low pressured cavity. Use of a dual purposesupport/cooling air distribution component can be accommodated thesupport and cooling of the CMC seal segment. A perimeter seal member(sometimes called a gasket) lays on a thick layer of EnvironmentalBarrier Coating (EBC) to provide a smooth surface for the seal member toseal against. This EBC also acts as a thermal barrier coating, shieldingthe gasket from high temperatures and reducing the thermal gradient in aperimeter flange of the CMC seal segment.

In illustrative embodiments, a wave spring is positioned between abridge of the seal segment and a flow distributor of a track-segmentcoupler to bias the seal segment toward the carrier segment (made ofmetallic materials, such as Ni alloy for example) for mutual engagementwith the perimeter seal member. A metal washer and high temperaturecompliant gasket are positioned between a metallic nut and the carriersegment. The nut engages with the support shaft to preload the wavespring and gaskets to seal the cavity.

In illustrative embodiments, the perimeter seal member is pressurizedthrough forward ports. A pressure of the seal member at a fore end ofshroud is generally higher than the flow path pressure at a similaraxial location through the engine (e.g., before the turbine wheel).Likewise a pressure of seal member at an aft end of the shroud isgenerally higher than the flow path pressure at a similar axial locationthrough the engine (i.e., after the turbine wheel). The latter pressureis sometimes referred to as the pressure sink of the engine.

In illustrative embodiments, the CMC seal segment is drawn up againstthe gasket by a clamp load from the nut/shaft, exerted through the flowdistributor and wave spring. The clamp load of the nut/shaft is splitbetween securing the shaft to the carrier and sealing the gasket alongthe bottom flange of the CMC seal segment. This allows for the designoption of controlling the bending load and stress in the flange of theseal segment. Bending stress in the flange can be controlled byadjusting the load split of the nut/shaft clamp load.

In illustrative embodiments, the wave spring extends circumferentiallyalong the flow distributor between the bridge and the flow distributor.The wave spring may be made of metallic material, such as a Ni alloy forexample. The support shaft is coupled to the flow distributor afterinsertion through the bridge and the wave spring is preloaded bytightening the nut to hold the support shaft and seal segment on thecarrier segment. This establishes the contact between the gasket,carrier segment, and seal segment. The seal segment and spring worktogether spread the load out on the CMC seal segment backside surfaceand to lower the stress in this component. Additionally, the springadjusts the stiffness of the system to help the gasket between thecarrier and the seal segment maintain contact and sealing.

In illustrative embodiments, the Coefficient of Thermal Expansion (CTE)of Ni alloys is roughly triple the CTE of CMC. As temperatures areapplied to the metal carrier segment and CMC seal segment during engineoperation, the radii of the metal and CMC surfaces, at the interfaceswith the gasket, could differ significantly. This could lead to poorsealing of the gasket and load problems between the carrier and sealsegment. By machining the bottom side of the carrier and forming the topsurface of the CMC seal segment on different radii or different radiuscenters when cold, this interface can also be optimized for when theengine is at operating temperatures and pressures. Similarly, the radiiof the metal flow distributor and CMC seal segment could differsignificantly. This could lead to an uneven loading of the wave springthat is between the flow distributor and seal segment. By machining theflow distributor and/or forming the CMC seal segment on different radiior different radius centers when cold, the contact between the wavespring, the flow distributor, and the seal segment, can also beoptimized for when the engine is at operating temperatures andpressures.

In illustrative embodiments, by modifying the wavelength and/oramplitude of the waves of the wave spring, the contact and loadingbetween the wave spring, flow distributor, and seal segment could beoptimized for when the engine is at operating temperatures andpressures. For example, the wavelength of the spring could be decreasednear the ends of the spring to make the spring stiffer in these regions.Or the amplitude of the spring's waves could be decreased near themiddle of the spring to facilitate a contact state that might be desiredwhen the system is at engine operating temperatures and pressures. Othersystems of springs can be used to adjust the stiffness of the system,such as coil, leaf, and torsional springs.

In illustrative embodiments, the wave spring could be cut axially alonga middle portion thereof to allow for the control of the loads, andtherefore the stresses, that are introduced into the CMC seal segment.Due to the hole in the wave spring that accommodates the support shaft,the contact loads imparted by the peak of the one wave of the wavespring at this location can be quite high. Cutting the peak of this onewave reduces its stiffness and the load it generates on the sealsegment.

In illustrative embodiments, the carrier segments include an enclosedcavity outward of the CMC seal segment. The perimeter gasket between thecarrier and CMC seal segment seals this cavity. The enclosed cavity canbe charged with air of a much lower pressure (such as interstagecompressor bleed air) than cooling air from other sources (such ascompressor discharge air). Using interstage compressor air to cool theseal segment represents a specific fuel consumption (SFC) savings forthe engine in that interstage compressor air has less work in it thancompressor discharge air. The air being supplied can be as low as asmall margin above the pressure sink. In addition to providing a supportfor the seal segment, the flow distributor distributes cooling air forimpingement on the seal segment.

In illustrative embodiments, cooling air following impingement isreturned to the flow path through outlet ports in the carrier segment.The size and number of these vent holes can control the pressure in thecavity above the seal segment. Vent holes communicate directly with theflow path pressure. Vent holes can be sized to reduce the cavitypressure to about 5% above flow path pressure, for example. By having alow pressure in this cavity, loading on the seal segment is minimizedand maximizes cooling effectiveness from the impingement. The vent holesmaximize control over the cavity pressure compared to using seal leakagewhich can have unknown variables.

In illustrative embodiments, the seal segment support/spring andimpingement cooling air assembly provides a largely variable system ofcontact compliance for the support of the seal segment. A variety ofsprings and support shapes are available for this system, allowing for agreat deal of control of the loads and stresses that are applied to theseal segment. In addition to carrying the seal segment, the flowdistributor provides a largely variable system for the impingement,conduction, and convection cooling of the seal segment, carrier segment,and the flow distributor itself. In this way, the thermal stress in theseal segment can be managed to be below the stress allowables of the CMCmaterial.

In illustrative embodiments, the perimeter seal member is fitted in achannel of the carrier segment. The channel includes a high pressurebuffer groove to feed high pressure air to the channel in case of gasketfailure. The groove includes supply holes for supplying high pressurebuffer air to the groove. High-pressure air is used in a fore section ofthe groove to keep flow path pressure out in the event of gasketfailure. For example, this might be compressor discharge air pressure.The perimeter gasket periodically has holes through its thickness sothat high-pressure air is available to prevent any flow path ingressalong the bottom face of the gasket. Should the gasket fail, compressordischarge air would prevent flow path gasses from entering the cavity ofthe carrier segment which may be at a pressure below the flow pathpressure before the turbine wheel. Also, the gasket is recessed into thecarrier segment so that it is restrained, minimizing deformation underpressure and loading.

In illustrative embodiments, forming dams in the groove allows the useof multiple buffer groove pressures. More than one dam can be employedto facilitate additional buffer pressures. By creating a solid dam inthis groove, air of different pressures can be used to block ingressinto the carrier cavity should there be a gasket failure. This is usefulin that the amount of air pressure in each section of buffer groove canbe tailored to purge against the flow path pressure at that axiallocation. This approach minimizes the leakage from the buffer groove,and allows for the use of air in the buffer groove with a lower amountof work invested. For example, lower buffer pressure used in an aftsection could be lower work compressor bleed air. Air in this groovewould still be some margin over the flow path pressure to block ingress.By employing the vent ports in the carrier, the trailing edge groovecould be either eliminated (filled in) or not pressured at all. Nothaving this trailing edge buffer groove entirely eliminates a source ofseal leakage and represents a decrease in SFC. This is all due tokeeping the cavity pressure a small margin above the flow path pressureaft of the turbine blade. A low internal cavity pressure compared to thehigh pressure in the forward portion of the perimeter gasket makes thesystem less sensitive to variations in leakage of air from this channel.

In illustrative embodiments, springs to enforce sealing contact can belocated outside the carrier segment. With a location outside thecarrier, temperature control of the springs may be maximized. With thesprings located outside the carrier, the height of the bridge of theseal segment can become shorter.

In illustrative embodiments, an W-shaped metallic spring seal is usedaround the perimeter of the blade track segment. High pressure air issupplied to the buffer groove in the carrier segment in case of sealfailure. The pressure of this air would be set at some margin above flowpath pressure, to prevent hot air ingress into the cavity of the carriersegment in case of seal failure. This high pressure air also energizesthe E seal causing it to seal at the peaks engaged with the blade tracksegment and the ends of the arms engaged with the groove of the carrier.

In illustrative embodiments, one or more multi-fold metallic springseals are used around the perimeter of the blade track segment. Highpressure air is supplied to the buffer groove in carrier in case of sealfailure. The pressure of this air would be set at some margin above flowpath pressure, to prevent hot air ingress into the cavity of the carriersegment in case of seal failure. This high pressure air also energizesthe multi-fold seals causing them to seal at the ends of the arms; oneengaged with the blade track segment and the other engaged with thegroove of the carrier.

According to an aspect of the present disclosure, a turbine shroudsegment may include a carrier segment comprising metallic materials, ablade track segment comprising ceramic matrix composite materials, and aseal member. The carrier segment may be formed to define anattachment-receiving space. The blade track segment may be formed toinclude a runner shaped to extend partway around a central axis and anattachment portion that extends radially outward from the runner intothe attachment-receiving space channel formed by the carrier segment. Aseal member may be configured to resist the movement of gasses into theattachment-receiving space. The seal member may be shaped to extendaround the attachment portion of the blade track segment and may bearranged to engage a radially-outwardly facing surface of the runner.

In illustrative embodiments, the seal member may be a one-piececomponent that extends all the way around the attachment portion of theblade track segment and along a perimeter edge of the runner.

In illustrative embodiments, the seal member may be formed to include aplurality of radially-extending bleed holes adapted to conduct a flow ofbuffer air through the seal member to resist the movement of gasses intothe attachment-receiving space.

In illustrative embodiments, the plurality of bleed holes may be formedonly along a leading edge of the blade track segment.

In illustrative embodiments, the seal member may comprise mica.

In illustrative embodiments, the runner of the blade track segment mayinclude a layer of environmental barrier coating that provides theradially-outwardly facing surface of the runner engaged by the sealmember.

In illustrative embodiments, the blade track segment may includeuncoated portions. The coating applied to a radially-outwardly facingsurface of the runner included in the blade track segment may besmoother than the uncoated portions of the blade track segment.

In illustrative embodiments, the carrier segment may include a mountplate and a plurality of receiving walls that extend inwardly in aradial direction from the mount plate toward the central axis. Thereceiving walls may extend all the way around the attachment portion ofthe blade track segment. The attachment-receiving space may be definedby the mount plate and the receiving walls. The seal member may extendradially between the receiving walls of the carrier and the runner ofthe blade track segment to resist the movement of gasses into and out ofthe attachment-receiving space.

In illustrative embodiments, the plurality of receiving walls may beformed to include seal channels that extends outwardly in the radialdirection and the seal channels receive the seal.

In illustrative embodiments, the seal channels may be formed by thereceiving walls open into one another and cooperate to form a continuouschannel that extends all the way around the attachment portion of theblade track segment.

In illustrative embodiments, the seal member may include at least onemetallic member shaped to form at least one U-shaped lobe that defines apressure-activated channel. The pressure-activated channel may bearranged to open into the seal channels. The seal member may beconfigured to expanded when pressurized air is supplied to the sealchannels.

In illustrative embodiments, the metallic member may be a one-piececomponent that extends all the way around the attachment portion of theblade track segment and along a perimeter edge of the runner.

In illustrative embodiments, the metallic member may be configured toexpand in an axial direction along the central axis when pressurized airis supplied to the seal channels.

In illustrative embodiments, the metallic member may be configured toexpand in the radial direction when pressurized air is supplied to theseal channels.

In illustrative embodiments, the seal member may include two metallicmembers. Each metallic member may be shaped to form at least oneU-shaped lobe that defines a pressure-activated channel arranged to openinto the seal channels. Each metallic member may be a one-piececomponent that extends all the way around the attachment portion of theblade track segment.

According to an aspect of the present disclosure, a turbine shroud mayinclude a carrier comprising metallic materials, a blade trackcomprising ceramic matrix composite materials, and a seal member. Thecarrier may be formed to define an attachment-receiving space. The bladetrack may be formed to include a runner shaped to extend at leastpartway around a central axis and an attachment portion that extendsradially outward from the runner into the attachment-receiving spacechannel formed by the carrier segment. The seal member may be configuredto resist the movement of gasses into the attachment-receiving space.The seal member may be arranged to engage a radially-outwardly facingsurface of the runner.

In illustrative embodiments, the carrier may include a mount plate andat least one receiving wall that extends inwardly in a radial directionfrom the mount plate toward the central axis. The at least one receivingwall may be formed to include a seal channel that extends outwardly inthe radial direction. The seal channel may be configured to receive theseal member.

In illustrative embodiments, the runner of the blade track may include alayer of environmental barrier coating that provides theradially-outwardly facing surface of the runner engaged by the sealmember. The blade track segment may include uncoated portions. Thecoating applied to the radially-outwardly facing surface of the runnerincluded in the blade track segment may be smoother than the uncoatedportions of the blade track segment.

In illustrative embodiments, the seal member may be formed to include aplurality of radially-extending bleed holes adapted to conduct a flow ofbuffer air through the seal member to resist the movement of gasses intothe attachment-receiving space. The plurality of bleed holes may beformed only along a leading edge of the blade track.

In illustrative embodiments, the seal member may comprise mica.

According to an aspect of the present disclosure, a turbine shroudsegment adapted for use in a gas turbine engine may include a carriersegment comprising metallic materials, a blade track segment comprisingceramic matrix composite materials, and an attachment assembly. Thecarrier segment may be formed to include an attachment-receiving space.The blade track segment may be formed to include a runner shaped toextend at least partway around a central axis and an attachment boxportion that extends radially outward from the runner into theattachment-receiving space formed by the carrier segment. The attachmentassembly may include an attachment post that extends from the carriersegment into the attachment box portion of the blade track segment. Theattachment post may be formed to include a post passageway that providespart of a cooling system configured to conduct cooling air into theattachment box portion of the blade track segment to cool the bladetrack segment when the turbine shroud segment is used in a gas turbineengine.

In illustrative embodiments, the attachment assembly may include anattachment support arranged inside the attachment box portion of theblade track segment that is coupled to the attachment post. Theattachment support may be formed to include distribution passagewaysfluidly coupled to the post passageway formed in the attachment post sothat cooling air conducted through the post passageway is distributed tovarious locations along the blade track segment when the turbine shroudsegment is used in a gas turbine engine.

In illustrative embodiments, the distribution passageways may extendaxially along the central axis and circumferentially around the centralaxis.

In illustrative embodiments, the attachment post may extend into theattachment box portion of the blade track segment through an attachmenthole formed in the attachment box portion. The attachment support may besized to block withdrawal of the attachment post out of the attachmentbox portion.

In illustrative embodiments, the attachment post may include a shaft andsupport threads formed on the shaft that engage the attachment supportto couple the attachment post to the attachment support.

In illustrative embodiments, the distribution passageways may be formedby the attachment support are arranged to discharge cooling air atvarious locations toward a radially-outwardly facing surface of therunner included in the blade track segment.

In illustrative embodiments, the attachment post may extend through apost hole formed in the carrier segment into the attachment-receivingspace formed by the carrier segment and through an attachment holeformed in the attachment box portion of the blade track segment.

In illustrative embodiments, the carrier segment may be formed toinclude an inlet passageway fluidly coupled to the post passagewayformed in the attachment post so that cooling air introduced into theinlet passageway is conducted through the post passageway into theattachment box portion of the blade track segment when the turbineshroud segment is used in a gas turbine engine.

In illustrative embodiments, the attachment box portion included in theblade track segment may define a box interior bounded by aradially-outwardly facing surface of the runner included in the bladetrack segment so that cooling air conducted into the box interior by thepost passageway cools the radially-outwardly facing surface of therunner.

In illustrative embodiments, the box interior defined by the attachmentbox portion of the blade track segment may be open for fluidcommunication with the attachment-receiving space formed by the carriersegment and the carrier segment may be formed to include a plurality ofvent holes arranged along an aft side of the carrier segment that areconfigured to conduct used cooling air out of the attachment-receivingspace.

According to an aspect of the present disclosure, a turbine shroudsegment adapted for use in a gas turbine engine may include a carriersegment comprising metallic materials, a blade track segment comprisingceramic matrix composite materials, and an attachment assembly. Thecarrier segment may be formed to include an attachment-receiving space.The blade track may be formed to include a runner shaped to extend atleast partway around a central axis and an attachment portion thatextends radially outward from the runner into the attachment-receivingspace formed by the carrier segment. The attachment assembly may includean attachment post that extends from the carrier segment through anattachment hole formed in the attachment portion of the blade tracksegment and an attachment support coupled to the attachment post toblock withdrawal of the attachment post through the attachment hole. Theattachment post may be formed to include a post passageway configured toconduct cooling air.

In illustrative embodiments, the attachment post may include a shaft andsupport threads formed on the shaft that engage the attachment supportto couple the attachment post to the attachment support.

In illustrative embodiments, the attachment support may be formed toinclude distribution passageways fluidly coupled to the post passageway.

In illustrative embodiments, the attachment support may be shaped toextend at least partway around the central axis.

In illustrative embodiments, the distribution passageways may extendaxially along the central axis and circumferentially around the centralaxis.

In illustrative embodiments, the distribution passageways formed by theattachment support may be arranged to discharge cooling air at variouslocations toward a radially-outwardly facing surface of the runnerincluded in the blade track segment.

In illustrative embodiments, the attachment post may extend through apost hole formed in the carrier segment into the attachment-receivingspace formed by the carrier segment.

In illustrative embodiments, the carrier segment may be formed toinclude an inlet passageway fluidly coupled to the post passagewayformed in the attachment post.

In illustrative embodiments, the carrier segment may be formed toinclude a plurality of vent holes that extend out of theattachment-receiving space configured to conduct used cooling air out ofthe attachment-receiving space.

In illustrative embodiments, the plurality of vent holes may be arrangedalong an aft side of the carrier segment.

According to an aspect of the present disclosure, a turbine shroudsegment may include a carrier segment comprising metallic materials, ablade track segment comprising ceramic matrix composite materials, and aseal member. The carrier segment may include a mount plate and aplurality of receiving walls that extend inwardly in a radial directionfrom the mount plate toward a central axis to define anattachment-receiving space. The blade track segment may be formed toinclude a runner shaped to extend partway around a central axis and anattachment portion that extends radially outward from the runner intothe attachment-receiving space channel formed by the carrier segment.The seal member may extend radially between the receiving walls of thecarrier segment and the runner of the blade track segment to resist themovement of gasses into the attachment-receiving space. At least one ofthe receiving walls included in the carrier segment may be formed toinclude buffer air passageways configured to discharge buffer air alongthe seal member to resist the movement of gasses into theattachment-receiving space.

In illustrative embodiments, the buffer air passageways may be arrangedalong an axially forward side of the carrier segment.

In illustrative embodiments, the plurality of receiving walls may beformed to include a seal channel that extends outwardly in the radialdirection and the seal channel receives the seal member.

In illustrative embodiments, the seal channel formed by the receivingwalls may extend all the way around the attachment portion of the bladetrack segment.

In illustrative embodiments, the buffer air passageways may be locatedto discharge buffer air into the seal channel formed by the receivingwalls.

In illustrative embodiments, the plurality of receiving walls of thecarrier segment may be formed to include at least one buffer groove thatextends outwardly in the radial direction into the receiving walls. Theat least one buffer groove may be arranged radially outward of at leasta portion of the seal member. The buffer air passageways may be locatedto discharge buffer air into the at least one buffer groove formed bythe receiving walls.

In illustrative embodiments, the plurality of receiving walls may beformed to include a seal channel that receives the seal member. Thebuffer groove may be smaller than the seal channel. The buffer groovemay extend outward in the radial direction from the seal channel.

In illustrative embodiments, the receiving walls of the carrier segmentmay be formed to include at least one buffer dam that extends into thebuffer groove and the buffer dam may be sized to restrict the flow ofbuffer air through the buffer groove so that different portions of thebuffer groove are pressurized at different levels when buffer air issupplied to the buffer groove from the buffer air passageways.

In illustrative embodiments, the buffer groove may extend all the wayaround the attachment-receiving space defined by the carrier segment.

In illustrative embodiments, the seal member may be formed to include aplurality of radially-extending bleed holes adapted to conduct bufferair through the seal member.

In illustrative embodiments, the plurality of bleed holes may be formedonly along a leading edge of the blade track segment.

In illustrative embodiments, the plurality of bleed holes may each bealigned with a buffer air passageway formed in the carrier segment toreceive buffer air being conducted through the buffer air passageway.

According to an aspect of the present disclosure, a turbine shroudsegment may include a carrier segment comprising metallic materials, ablade track segment comprising ceramic matrix composite materials, and aseal member. The carrier segment may include a mount plate and a wallthat extends inwardly in a radial direction from the mount plate towarda central axis. The blade track segment may be formed to include arunner shaped to extend partway around a central axis. The seal membermay extend radially between the wall of the carrier segment and therunner of the blade track segment to resist the movement of gassesbetween the wall of the carrier segment and the runner of the bladetrack segment. The wall included in the carrier segment may be formed toinclude a plurality of buffer air passageways configured to dischargebuffer air along the interface of the carrier segment and the sealmember.

In illustrative embodiments, the wall of the carrier segment may beformed to include a buffer groove that extends outwardly in the radialdirection. The buffer groove may be arranged radially outward of atleast a portion of the seal member. The buffer air passageways may belocated to discharge buffer air into the buffer groove.

In illustrative embodiments, the wall may be formed to include a sealchannel that receives the seal. The buffer groove may be smaller thanthe seal channel. The buffer groove may extend outward in the radialdirection from the seal channel.

In illustrative embodiments, the wall of the carrier segment may beformed to include at least one buffer dam that extends into a buffergroove and the buffer dam may be sized to restrict the flow of bufferair along the buffer groove so that different portions of the buffergroove are pressurized at different levels when buffer air is suppliedto the buffer groove from the buffer air passageways.

In illustrative embodiments, the seal member may be formed to include aplurality of radially-extending bleed holes adapted to conduct bufferair through the seal member.

In illustrative embodiments, the plurality of bleed holes may be formedonly along a leading edge of the blade track segment.

In illustrative embodiments, the plurality of bleed holes may be eachaligned with a buffer air passageway formed in the carrier segment toreceive buffer air being conducted through the buffer air passageway.

In illustrative embodiments, the plurality of buffer air passageways maybe formed only along a leading edge of the wall included in the carriersegment.

According to an aspect of the present disclosure, a turbine shroudsegment adapted for use in a gas turbine engine may include a carriersegment comprising metallic materials, a blade track segment comprisingceramic matrix composite materials, and an attachment assembly. Thecarrier segment may be formed to include an attachment-receiving space.The blade track segment may be formed to include a runner shaped toextend at least partway around a central axis and an attachment portionthat extends radially outward from the runner into theattachment-receiving space formed by the carrier segment. The attachmentassembly may include an attachment post that extends from the carriersegment through an attachment hole formed in the attachment portion ofthe blade track segment. An attachment support may be coupled to theattachment post to block withdrawal of the attachment post through theattachment hole. A load distributor may be configured to distributeclamp force applied by the attachment post and the attachment supportalong the attachment portion of the blade track segment.

In illustrative embodiments, the load distributor may include a wavespring arranged radially between the attachment portion of the bladetrack segment and the attachment support of the attachment assembly.

In illustrative embodiments, the wave spring may be formed to includewaves having a varying frequency along the length of the wave spring.

In illustrative embodiments, the waves of the wave spring may vary infrequency as the wave spring extends away from the attachment post.

In illustrative embodiments, the waves of the wave spring may have avarying amplitude along the length of the wave spring.

In illustrative embodiments, the wave spring may be formed to includewaves having a varying amplitude along the length of the wave spring.

In illustrative embodiments, the waves of the wave spring may increasein amplitude as the wave spring extends away from the attachment post.

In illustrative embodiments, the attachment post may extend through anaperture formed in the wave spring.

In illustrative embodiments, the load distributor may include a firstwave spring and a second wave spring. The first wave spring may bearranged to extend circumferentially from the attachment post in a firstdirection and may be located radially between the attachment portion ofthe blade track segment and the attachment support of the attachmentassembly. The second wave spring may be arranged to extendcircumferentially from the attachment post in a second direction,opposite the first direction, and may be located radially between theattachment portion of the blade track segment and the attachment supportof the attachment assembly.

In illustrative embodiments, the first wave spring may be formed toinclude a notch through which a portion of the attachment post extendsand the second wave spring is formed to include a notch through which aportion of the attachment post extends.

According to an aspect of the present disclosure, a turbine shroudsegment adapted for use in a gas turbine engine may include a carriersegment comprising metallic materials, a blade track segment comprisingceramic matrix composite materials, and an attachment assembly. Thecarrier segment may be formed to include an attachment-receiving space.The blade track segment may be formed to include a runner shaped toextend at least partway around a central axis and an attachment portionthat extends radially outward from the runner into theattachment-receiving space formed by the carrier segment. The attachmentassembly may include a first attachment post that extends from thecarrier segment through an attachment hole formed in the attachmentportion of the blade track segment, a first attachment support arrangedinside a cavity formed by the attachment portion of the blade tracksegment and coupled to the first attachment post to block withdrawal ofthe attachment post through the attachment hole, and a first springmember arranged outside of the attachment-receiving space and configuredto pull the first attachment support radially outward away from thecentral axis.

In illustrative embodiments, the first spring member may be arrangedradially outward of the carrier segment.

In illustrative embodiments, the first spring member may be a coilspring that engages a radially-outwardly facing surface of the carriersegment.

In illustrative embodiments, the first attachment support may extendcircumferentially within the cavity formed by the attachment portion ofthe blade track segment.

In illustrative embodiments, the first attachment support may beyoke-shaped and contacts the attachment portion of the blade tracksegment at locations spaced apart from the attachment hole formed in theattachment portion of the blade track segment.

In illustrative embodiments, the attachment assembly may include asecond attachment post that extends from the carrier segment through anattachment hole formed in the attachment portion of the blade tracksegment, a second attachment support arranged inside a cavity formed bythe attachment portion of the blade track segment and coupled to thesecond attachment post to block withdrawal of the second attachment postthrough the attachment hole, and a second spring member arranged outsideof the attachment-receiving space and configured to pull the secondattachment support radially outward away from the central axis.

In illustrative embodiments, the first attachment post, the firstattachment support, and the first spring member may be spacedcircumferentially apart from the second attachment post, the secondattachment support, and the second spring member.

In illustrative embodiments, the first attachment post, the firstattachment support, and the first spring member may be spaced axiallyapart from the second attachment post, the second attachment support,and the second spring member.

In illustrative embodiments, the first attachment post, the firstattachment support, and the first spring member may be spaced axiallyapart from the second attachment post, the second attachment support,and the second spring member.

In illustrative embodiments, the first attachment support included inthe attachment assembly may be arranged inside a first cavity formed bythe attachment portion of the blade track segment and the secondattachment portion of the attachment assembly may be arranged inside asecond cavity formed by the attachment portion of the blade tracksegment.

While the disclosure has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asexemplary and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of thedisclosure are desired to be protected.

What is claimed is:
 1. A turbine shroud segment adapted for use in a gasturbine engine having a central axis, the turbine shroud segmentcomprising a carrier segment comprising metallic materials, the carriersegment formed to include an attachment-receiving space, a blade tracksegment comprising ceramic matrix composite materials, the blade tracksegment formed to include a runner shaped to extend at least partwayaround the central axis and an attachment portion that extends radiallyoutward from the runner into the attachment-receiving space formed bythe carrier segment, an attachment assembly including an attachment postthat extends from the carrier segment through an attachment hole formedin the attachment portion of the blade track segment, an attachmentsupport coupled to the attachment post to block withdrawal of theattachment post through the attachment hole, and a load distributorconfigured to distribute clamp force applied by the attachment post andthe attachment support along the attachment portion of the blade tracksegment.
 2. The turbine shroud segment of claim 1, wherein the loaddistributor includes a wave spring arranged radially between theattachment portion of the blade track segment and the attachment supportof the attachment assembly.
 3. The turbine shroud segment of claim 2,wherein the wave spring is formed to include waves having a varyingfrequency along the length of the wave spring.
 4. The turbine shroudsegment of claim 3, wherein the waves of the wave spring vary infrequency as the wave spring extends away from the attachment post. 5.The turbine shroud segment of claim 3, wherein the waves of the wavespring have a varying amplitude along the length of the wave spring. 6.The turbine shroud segment of claim 2, wherein the wave spring is formedto include waves having a varying amplitude along the length of the wavespring.
 7. The turbine shroud segment of claim 6, wherein the waves ofthe wave spring increase in amplitude as the wave spring extends awayfrom the attachment post.
 8. The turbine shroud segment of claim 2,wherein the attachment post extends through an aperture formed in thewave spring.
 9. The turbine shroud segment of claim 1, wherein the loaddistributor includes a first wave spring and a second wave spring, thefirst wave spring is arranged to extend circumferentially from theattachment post in a first direction and is located radially between theattachment portion of the blade track segment and the attachment supportof the attachment assembly, and the second wave spring is arranged toextend circumferentially from the attachment post in a second direction,opposite the first direction, and is located radially between theattachment portion of the blade track segment and the attachment supportof the attachment assembly.
 10. The turbine shroud segment of claim 9,wherein the first wave spring is formed to include a notch through whicha portion of the attachment post extends and the second wave spring isformed to include a notch through which a portion of the attachment postextends.
 11. A turbine shroud segment adapted for use in a gas turbineengine having a central axis, the turbine shroud segment comprising acarrier segment comprising metallic materials, the carrier segmentformed to include an attachment-receiving space, a blade track segmentcomprising ceramic matrix composite materials, the blade track segmentformed to include a runner shaped to extend at least partway around thecentral axis and an attachment portion that extends radially outwardfrom the runner into the attachment-receiving space formed by thecarrier segment, an attachment assembly including an attachment postthat extends from the carrier segment through an attachment hole formedin the attachment portion of the blade track segment, an attachmentsupport coupled to the attachment post to block withdrawal of theattachment post through the attachment hole, and a spring arrangedradially between the attachment portion of the blade track segment andthe attachment support of the attachment assembly.
 12. The turbineshroud segment of claim 11, wherein the spring is a wave spring.
 13. Theturbine shroud segment of claim 11, wherein the attachment post extendsthrough an aperture formed in the spring.